Part of the proposal will investigate the role of the interstitial cells of the kidney in various forms of experimental hypertension. There is evidence to show that these cells produce an antihypertensive principle which on the basis of recent work is probably one or several of the prostaglandins. We have developed a method for chemically amputating the papilla of the rat thus depriving the animal of interstitial cells. We wish to study various forms of experimental hypertension such as "clip" and steroid hypertension in this model and to investigate the effects of absence of papilla on various other aspects of hypertension, in particular its relationship to what has been called renoprival hypertension. Most of our efforts are being directed to studies on the blood flow and vasculature in acute renal failure induced in the rat and rabbit by both mercuric chloride and glycerol. The various techniques being used are measurement of total blood flow, medullary plasma flow, and in-vivo angiography. We are also studying the effects of prostaglandin inhibition, using indomethacin, in control rats and in those with acute renal failure of the two types mentioned.